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Distinct functional and structural MRI abnormalities in mesial temporal lobe epilepsy with and without hippocampal sclerosis
Author(s) -
Coan Ana C.,
Campos Brunno M.,
Beltramini Guilherme C.,
Yasuda Clarissa L.,
Covolan Roberto J. M.,
Cendes Fernando
Publication year - 2014
Publication title -
epilepsia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.687
H-Index - 191
eISSN - 1528-1167
pISSN - 0013-9580
DOI - 10.1111/epi.12670
Subject(s) - hippocampal sclerosis , ictal , precuneus , temporal lobe , epilepsy , electroencephalography , psychology , neuroscience , atrophy , hippocampal formation , medicine , pathology , functional magnetic resonance imaging
Summary Objective We aimed to investigate patterns of electroencephalography ‐correlated functional MRI ( EEG ‐f MRI ) and subtle structural abnormalities in patients with mesial temporal lobe epilepsy ( MTLE) with hippocampal sclerosis ( MTLE ‐ HS ) or normal MRI ( MTLE ‐ NL ). Methods We evaluated EEG ‐f MRI acquisition of the 25 patients with diagnosis of MTLE who had interictal epileptiform discharges ( IED s) in the intra‐ MRI EEG : 13 MTLE ‐ HS and 12 MTLE ‐ NL . f MRI was performed using echo‐planar images in a 3T MRI coupled with EEG acquired with 64 MRI ‐compatible electrodes. In the first level analyses, the time of the IED s ipsilateral to the epileptogenic zone was used as the paradigm, and four contrasts maps were built according to the variation of the hemodynamic response function ( HRF ) peaks (0, +3, +5, and +7 s). Second level group analyses were performed combining the contrast maps of MTLE ‐ HS or MTLE ‐ NL patients with each different HRF obtained at the first level. Areas of gray matter atrophy were evaluated with voxel‐based morphometry ( VBM ) in both groups. Results MTLE ‐ HS and MTLE ‐ NL had IED ‐related positive BOLD (pos BOLD ) detected in the ipsilateral anterior temporal lobe and insula. However, only MTLE ‐ HS had significant pos BOLD on contralateral hippocampus and anterior cingulate, whereas MTLE ‐ NL had areas of pos BOLD on ipsilateral frontal lobe. Both groups had significant IED ‐related neg BOLD responses in areas of the default mode network ( DMN ), such as posterior cingulate and precuneus. There was no overlap of both pos BOLD and neg BOLD and areas of atrophy detected by VBM . Significance Similar IED s have different patterns of hemodynamic responses in sub‐groups of MTLE . In both MTLE ‐ HS and MTLE ‐ NL , there is a possible suppression of the DMN related to IED s, as demonstrated by the neg BOLD in these areas. The brain areas involved in the interictal related hemodynamic network are not the regions with the most significant gray matter atrophy in MTLE with or without MRI signs of HS . A PowerPoint slide summarizing this article is available for download in the Supporting Information section here .